Radar scanner apparatus



Feb. 27, 1951 T. l. MOSELEY RADAR SCANNER APPARATUS 10 Sheets-Sheet 1 Filed April 15, 1947 INVENTOR. 720707750 1'. MQFrf/Ey Feb. 27, 1951 T. 1. MOSELEY 2,543,188

RADAR SCANNER APPARATUS Filed April 15, 1947 10 Sheets-Sheet 2 Feb. 27, 1951 T. 1. MOSELEY J RADAR SCANNER APPARATUS Filed April 15, 1947 10 Sheets-Sheet 5 Plan! INVENTOR. 75/71/0750 I Masa/ey Feb. 27, 1951 'r. l. MOSELEY RADAR SCANNER APPARATUS F iled April 15, 1947 10 Sheets-Sheet 4 IN V EN TOR. 7201/f/750/7 [Mose/6y Feb. 27, 1951 Q T. l. MQSELEY 2,543,188

RADAR SCANNER APPARATUS Filed April 15, 1947 10 Sheets-Sheet 7 Feb. 27, 1951 T. 1. MOSELEY 2,543,188

RADAR SCANNER APPARATUS Filed April 15, 1947 10 Sheets-Sheet 8 /7J I fiat; L /76 F W MT? INVENTOR. 70/27/0750 1'. Mose/6y Feb. 27, 1951 T. l. MOSELEY 2,543,188

RADAR SCANNER APPARATUS Filed April 15, 1947 10 Sheets-Sheet 9 fife! g w Ma ML 0; /43

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73/7707150/7 f. Mae/.7 -BY Feb. 27, 1951 T. l. MOSELEY RADAR SCANNER APPARATUS 1O Sheets-Sheet 10 Filed April 15, 1947 INVENTOR. Tam/#250 f. Mose/5y Patented Feb. 27, 1951 UNITED STATES PATENT OFFICE 7 Claims.

The present invention-relates to radar apparatus, and more particularly to a scanning radar antenna mechanism operable with transmittingreceiving equipment for transmitting a radio frequency beam and iorreceiving reflections. of such beam from any target upon which it might impinge.

This invention is a continuation in part of my applications for Radar Scanner Unit, Serial No. 672,462, filed May 27, 1946, and Radar Scanner Unit, Serial No. 679,120, filed June 25, 1946, now Patent No. 2,479,539 granted August 16, 1949.

In the radar scanner units described in my aforesaid applications, and particularly inapplication Serial No. 679,120, an antenna, including a parabolic reflector and feed horn, may besimultaneously rotated about alongitudinal axis and caused to nod about an axis perpendicular to the rotational axis at two different nodding amplitudes, or the antenna can be caused to nod without rotation at the two different amplitudes of oscillation. Such selective scanning operations are performed mechanically and controlled electrically, which complicates the mechanism required and renders more difiicult its maintenance in proper and efiective operating condition. Accordingly, it is an object of thepresent invention to provide an improved radar scanning antenna apparatus whose antenna can be simultaneously rotated and nodded, or nodded alone, in response to selective electrical controls.

A further object of the invention is to provide radar scanning antenna apparatus having an antenna operable at a plurality of nodding speeds.

Still another object of the invention is to provide a radar scanning apparatusembodying an antenna capable of operation at a plurality of nodding speeds both during its nodding only (azimuth or horizontal scanning) and during its combined rotation and nodding (spiral scanning).

Yet a further obj ectof the invention is to provide an improved device for positioning the nodding axis of the antenna vertically when it is desired to perform azimuth or horizontal scanning only. In a more limited sense, this objective involves the provision of electric controlled instrumentalities which automatically erect the nodding axis to the vertical upon positioning of the controls for azimuth scanning only.

- Another object of the invention resides in the provision of a radar scanning apparatus having an antenna which is capable of being tilted to the horizontal.

A further. object of. the invention is to provide a radar scanning apparatus having an antenna which can be tilted to the: horizontal, being selectively inclinable both above and below the horizontal during azimuth scanning or nodding alone.

Yet another object of the invention is to provide: a radar scanning apparatus having an antenna which may be rotated about a longitudinal axis, nodded'about an axis perpendicular to the rotational axis, and tilted about an axis perpendicular to the other two axes, such motions being selectively performable to obtain simultaneously rotation and nodding, nodding alone or combined nodding and tilting.

Still a further object of the invention is to prevent rotation of the'antenna in a normal direction unless its tilt angle is zero.

Another object of the invention is to automatically restore the tilt angle of the antenna to zero when rotation of the antenna is desired, and to preclude such rotation until the antenna has assumed its zero tilt Position.

A further object of the invention is to provide for the automatic tilting of the antenna of a radar scanner apparatus to the degree preselected by the apparatus controls.

Yet a further object of the invention is to automatically restore the tilt angle of the antenna to zero when rotation of the antenna is desired and to retilt the antenna to the previous selected. tilt angle upon discontinuing its rotation.

In its general aspects, the invention contemplates a radar scanning apparatus embodying an antenna, which includes a parabolic reflector and feed horn. The antenna can be rotated by means of an electric motor and intervening mechanism; it may also be nodded by a separate electric motor and intervening mechanism; and its reflector may be tilted by means of a separate electric motor and intervening mechanism, the tilt angle 7 being either positive or negative, as desired and selected. The electric motor for rotating the antenna about a longitudinal axis operates substantially at a constant speed, and normally in a single direction. The electric motor for the nodding or azimuth drive is a two-speed reversible motor, operable at one speed and in one direction to control the setting of the oscillating mechanism to nod the antenna at one amplitude of oscillation, and rotatable in the opposite direction at a different speed to automatically modify the mechanism driven by it and oscillate or nod the antenna at a different amplitude of oscillation.

More particularly, the nodding or azimuth motor driving mechanism may effect the nodding or oscillation of the antenna through a wide angle at a slow speed, or through a narrower angle at a faster speed. The tilt motor and its associated mechanism may effect infinite gradations of tilting, either above or below the horizontal, within specified limits. The mechanism also includes a separate motor drive for operating an air pump, which has the purpose of pressurizing the feed horn and wave guide transmission line of the apparatus.

The apparatus has several selective and operable positions, under both manual and automatic controls. The manual control has an off position, in which nothing is operable; it may be shifted to a warm-up position, in which various motors may operate, providing in effect a standby condition; the controls may be shifted to provide for selective azimuth operation at zero, positive or negative tilting of the parabolic reflector; and the controls may be arranged for spiral scanning, in which the antenna is rotated and nodded at the same time.

As indicated above in the objects of the invention, the tilt position may vary from zero degrees to both a positive and negative angle, depending upon the desire to incline the axis of the reflector above or below the horizon. A tilt position can only be maintained and produced during horizontal scanning alone. An electric interlock is provided to prevent rotation of the antenna unless the tilt angle is zero. In the event that such rotation about the longitudinal axis i desired in the normal direction, the tilt angle, if other than zero, is automatically restored to zero before the circuit through the rotating motor can be completed.

Provision is also made for insuring that the axis about which the antenna nods or oscillates is vertical when azimuth or horizontal scanning alone is desired. This takes place through electrical instrumentalities which cause the main rotating motor to operate at a comparatively slow speed intermittently in a reverse direction, to position the axis of oscillation vertically,

The angle of tilt of the reflector may be preselected manually, and the reflector will automatically follow up to the preselected angle and maintain such angle. When rotation of the antenna is desired, the tilt angle is automatically restored to zero, but, if the manual preselected degree of tilt has not been changed or set to zero, discontinuance of the antenna rotation will cause the reflector to automatically reassume the former tilted position.

One form which the invention may assume is exemplified in the following description and illustrated by way of example in the accompanying drawings, in which:

Fig. 1 is a side elevation of a radar scanner antenna apparatus.

Fig. 2 is a partial longitudinal section on an enlarged scale taken along the line 2-2 on Fig. 1, and disclosing the mechanism. for rotating the antenna and also part of the device for tilting the reflector and for controlling its degree of tilt.

Fig. 3 is a longitudinal section through the apparatus, parts being shown in elevation.

Fig. 4 is a section taken along the line 44 on Fig. 2.

Fig. 5 is an enlarged isometric view, partly in section, of portions of the mechanism for nodding the antenna and also for effecting its tilting.

Fig. 6 is a section taken along the line 5-6 on Fig. 3.

Fig. 7 is a cross-section taken along the line l| on Fig. 3.

Fig. 8 is a. section taken along the line 8-8 on Fig. 3.

Fig. 9 is a side elevation of part of the mechanism for tilting the parabolic reflector.

Fig. 10 is a cross-section through the apparatus, disclosing parts of the nodding or azimuth scanning mechanism and parts of the tilt mechanism.

Fig, 11 is a section taken along the line llll on Fig. 10.

Fig. 12 is a section taken along the line l2l2 on Fig. 10.

Fig. 13 is a section taken along the line [3-13 on Fig. 10.

Fig. 14 is a section through the mechanism for operating the air pump and pulser mechanism.

Fig. 15 is a section taken along the line l5--l5 on Fig. 14.

Fig. 16 is an elevation of the pulser mechanism shown in Fig. 14, with its housing cover removed.

Fig. 1'7 is a section tak n along the line 11-11 on Fig. 3 of the erecting mechanism with its parts in one operative position.

Fig. 18 is a view similar to Fig. 17, with the parts disclosed in another operative position.

Fig. 19 is a schematic electrical circuit diagram of the control and operating mechanisms for determining the various positions and operations of the antenna.

In the form of the invention disclosed in the drawings, a main housing I0 is suitably secured within a spider ll whose arms l2 are attachable to a support l3 by means of bolts 14. Such support may be a nacelle of an aircraft, in which the radar scanner apparatus is mounted.

A tubular main spindle 15 extends longitudinally of the housing, being supported therein by suitable forward and rearward bearings l6, H, and constituting part of a wave guide transmission for the radio frequency energy. The rear of the spindle l5 communicates with a generally L-shaped, stationary rear wave guide l8 suitably secured to the rear of the housing 10, while the forward end of the spindle communicates with a forward wave guide in the form of an L-shaped laterally extending joint is whose for ward longitudinal portion 26 is secured within an inwardly directed, lateral wave guide 21 fixed to the outer end of a spindle arm 22 extending laterally from and secured to the forward portion of the spindle [5. This lateral wave guide 2! supports, through the intermediary of a suitable bearing 23, a lateral oscillating feed horn 24 whose oscillating shaft 25 extends on the other side of the longitudinal axis of the spindle I5 and is supported within a suitable bearing 26 carried on the end of an opposite lateral spindle arm 21 afnxed to the forward portion of the spindle.

A generally U-shaped bracket 28 is keyed, or otherwise suitably secured, on the outer end of the oscillatable feed horn shaft 25 (see Fig. 6), the opposed end of the bracket 28 being secured to a stub shaft 29 rotatably mounted within a bearing 30 mounted in the outer end of the lateral wave guide 2|. The rearwardly extending arms or portions 3| of the U-shaped bracket 28 carry suitable washers 32 for statically and dynamically balancing the rotating mechanism.

A longitudinal feed horn portion 33 communittts with an *s sbii'rttt bsc iiatiiifg fee-a is carried on the .U-shaped 'oscillatablebra'cket I 28, 'order to oscillate therewith durirfg azimuth scanning and spiral scanning. The feed horn 33 passes through an enlarged central holes? in the reflector 35 to permit tilting of the latter withrespect to the feed hom. i

Aparasitic dipole '38 is'pivotally m unted on a bracketv39 secured to the forward stern 332; of

the feed horn. The, dipole extends in opposite sides'of its longitudinal pivot axis and has one side weighted in order to allow centrifugaliorce resulting from spiral scan rotation to shift or fiip the dipole outer phase with the antenna exciting field so that it has no effect on the radiation pattern. During horizontal scanning, however, the dipole 38 is disposed horizontally and distorts the beam pattern by concentrating energy in the lower side 'of the beam.

In viewof theprovision for tilting thejp'arabolic reflector 35 about an axis'perpendi'cular to the nodding or azimuth scanning axis of the lateral feed horn 2A and oscillating speed shaft 25,

the reflector is not rigidly secured to the bracket '28. Instead, the opposed, rearwardly extending lugs 48 on the reflector head bracket are pivotally inountedon a pair of hinge pins 4], whose axis is perpendicular to the nodding "axis of thean- 'tenn'a, fitting within opposed, forwardly extending portions 42 of the U-shaped bracket (see Figs. land 8). V, I v

The reflector 35 is tiltable, and may be held in any angle of tilt within the range of the mechanism, either positive or negativa by apparatus now to be described. The reflector bracketBB is provided with a pair of rearwardly extending arms 33 on opposite sides of its longitudinal axis, which arms each carry a pivot pin 44 mounted within an arm 45 of a vertical yoke 46 secured to the central portion of a horizontal yoke 41 by a stud 48, whose inner portion is threaded to the central portion of the vertical yoke tfi an'd whose outer portion is threaded to the centralportion oi the horizontal yoke 41. The latter yoke extends rearwardly, with its bifurcated arms 49 disposed around the feed horn shaft 25 and carrying a pin 50 extending through an elongated slot in the shaft into a central shaft bore 52, where the pin 58 is secured to, a slide 53 guided by the wall of the shaft bore 52' and reciprocable therewithin. v

Reciprocation, or inward and outward lateral movement, of the 'slideEZ-S occurs as the result of moving a lever segment 54 having forward teeth 55'1neshing with rack teeth or ribs 56 on the slide 53, and whose rearward end is mounted upon a pivot pin 5i secured to tliespindle arm 27. Movement of the lever segment 54 about its pivot pin El and corresponding movement of the slide 53 occur as a result of rotating a cam 58 about a pivot pin 59 secured to the spindle arm 21. This cam has an outer canisurfacelop'erable upon a cam follower Bll'inountedbn 'th'el'e-' use ,offa bfolt tl ("see FigsjS and 9).

, extending into "the main housing l a. 'pin 19 of: the crank "arm is connected to one end mentor thefslide 53 forwardly or rearwardly corresponding'ly rotates the cam 53 on its pivot pin '59 and shift s'th'eilever segment 54about its pivot pin 51 to move the plunger 53 and yokes it, 4! and determine the extent of tiltoi the parabolic reflector 35 aboutthe'axis of the hinge pi nsdi. Engagement between the cam follower ill and camjSB is maintained by a pair of opposed tension springs '66, each spring having one end attached to "a, pin 44 connecting'an arm 43 with the vertical yoke 46, and its other end attached to the Ui fshap'ed bracket Z8 in a suitable manner, as by t V It is to be notedftliat the springs '86 tend to shift the verticalyoke lfifinwardly, to maintain "the follower 66 "engaged with thefcja'rn tsfan'd also tends to move the parabolic reflector 35 toward'a negative tilt position, i.f'e a position inclined downwardly to thehori'zontal. v V A The degree of tilt of therefie'ctor S5 "can be varied in accordance with the extent or rotation and direction of rotation of an electric tiltrfiotor 68 suitably secured to the main housing i 5 (see Figs. 3, '10 and 11 particularly). This tilt motor can be controlled for rotation in either direction in jordentomove thetilt slide 53 along the spindle 'i'fsfeitlierina forwarder a rearward direction, The tilt motor 63 is adapted, to shift the tilt slide 63 through a "gear reducing and crank and slide mechanism. In the form disclosed in the drawings, this mechanism includes a shaft 69 coupled iiO ZtiiGtiItIiIZOtOI armature shaft It and suitably jo-urnall'ed in a gear vcase IL The shaft'fi carries 'a worm i2 engageable with a worm gear liisecured to a cross-shaft l i 'journalledin the gear "case H. Another 'w'orr'n i5 is attached to this cross-shaft, meshing with a worm gear '16 a ffixed to a crankshaf ll rotatable in the case'fl'lfand. having a crank arm 13 The crank of "a connectingrod (see Fig. 3) whose other end is mounted upon a pin 81 secured to the rear 'portion of a tiit slide 32, extending "longitudinally of the main housing Iii parallel to the spindle l5, and guided for rectilinear movement within apairoi spaced brackets 83 secured to the 'main housing. QA scr ew84'se'cures this tilt slide 82 to a thrust bearingjoryoke 85 mounted within' a circumiereritial groovein a collar 8:) secured "to the tilt's'p'inolle s1ide63 in any suitable manner, 'as by means, of a'pin 8]. It is to be noted that the collar86 is freely rotatable within the thrust bearing 85 upon rotation of the spindle l5.

It is apparent that rotation of the tilt motor 68 in either selected direction correspondingly rotates the crank 13 and moves the tilt slide 82 longitudinally within its brackets 63 in the selectegldirection, causing the tilt slide rack. 63 to be moved longitudinally along the spindle i5'for the purpose of effecting tilting of the parabolic reflector '35 to the preselected angularity or degree of tilt through the agency ofjthe cam 53, lever 54, slide'53 and 'yokes 4%, cl, as abovedescribed. V I

The antenna, including the reflector 35 "and feed horn 24, 33, can also be nodded or oscillatedabout the axis of the feed horn shaft "25 through a mechanism now to be "described '(see particularly Figs. 5, 10; '12 and 13') i All 'a'zilniiith motor 88 is suitably secured to a gear case 89 and has a driving pinion 90 mounted on it armature shaft meshing with a gear 25 secured to a shaft 82 rotatably mounted in the gear case 89 and carrying a worm 93 engageable with a worm gear 94 fixed on a crankshaft 95 which extends from the gear case, where an adjustable crank pin mechanism 96 is attached thereto (see Figs. 10 and 13). The crank mechanism includes a pin 9'! connected to one end of a con necting rod 88, whose other end is mounted on a pin 99 attached to an arm I80 secured to a rack sector shaft I85 extending in one direction into the main spindle housing Ill, and in the opposite direction into an azimuth potentiometer housing I 02.

The inner end of the shaft IflI has a gear segment I53 secured to it meshing with a gear rack I04 fixed to a longitudinally extending slide I05, reciprocable lengthwise of the main housing It within guide supporting brackets IE5 secured within the housing It (see Fig. 2 for the slide and brackets). The reciprocating movement of the slide I95 is transmitted to a thrust bearing Iil'I secured to the slide by a screw 569. This thrust bearing I01 is received within a circumferential groove of a rotatable collar H fixed to a slide III by a coupling pin H2. The connection between the thrust bearing and collar is such as to allow the latter to rotate with the spindle in the former. The slide l I I is positioned within a longitudinal channel or groove H3 in the exterior of the spindle i5 located opposite to the tilt slide channel or groove 64, and has a rack H4 at its forward end whose teeth are engageable with a gear segment I55 fixed to the oscillatable feed horn shaft or transverse spindle of the scanner apparatus.

It is apparent that rotation of the motor 88 in either direction revolves the crank pin 9'! and oscillates the arm Iii?) through the intermediary of the connecting rod 98, correspondingly oscillating the shaft IBI and the gear segment I53 engageable with the reciprocable rack IN, reciprocating the slide I95 attached thereto, the collar SIS) rotatable with the spindle I5, and the spindle slide HI and rack II I, which, in turn, produces an oscillation of the antenna, including the feed horn 2 5, 33 and parabolic reflector 35, about the feed horn transverse axis.

The outer end of the oscillatable shaft it! has another gear segment I I6 attached thereto meshing with a gear II! fixed to the shaft II8 of an azimuth potentiometer Ht, which potentiometer operates in synchronism with the oscillation of the antenna 22, 33, to indicate the azimuth position of a beam reflected from a target on a viewer of the transmitter-receiver apparatus connected with the antenna. This synchronizing arrangement forms no part of the invention described in the present application, and requires no further details for an understanding of such invention.

The amplitude of oscillation or nod of the antenna may be varied by adjusting the throw of the crank pin 9'5. As disclosed in the drawings, the crank pin is secured to one end of a slide I29 mounted for radial movement within a head I2I and retained in such head by a suitable outer plate I22 attached to the head by screws I23, or the like. The pin 91? extends through a slot I24 in the plate, which permits radial movement of the pin 9? and slide 625 transversely of the head I2I. The other end of the slide I28 has a pin I25 therein extending through a slot I26 in the head 8 I2I and received within a spiral track I21 of a cam I28 rotatably mounted on a bearing I29 supported upon a boss I30 extending from the gear case 89. Rotation of this cam I28 is continually resisted by a brake device I3I bearing frictionally against the rear face I28a of the cam and secured to the gear case 89 in any suitable manner, as by means of rivets I32.

A change in the throw of the crank pin 91 occurs automatically, depending upon the direction of rotation of the azimuth motor 88. Assuming that the azimuth motor is rotated in one direction, the shaft 95, crank head I2 I crank slide I20 and crank pin 91 are rotated in a given direction, which may be assumed to be clockwise, as dis-- closed in Fig. 13. Such clockwise motion causes the follower pin I25 secured to the crank slide I20 to'move outwardly of the spiral cam track I2'I until it is disposed in its outermost position at the end I33 of such track. The tracking of the pin I25 to its outermost extent moves the crank pin 91 on the other side of the crank mechanism axis to its innermost position, thus decreasing the throw of the crank pin, and correspondingly decreasing the amplitude of oscillation of the antenna. In the operation of the adjustable crank device 95, the rotation of the cam I28 is at first resisted by the friction brake I3I, until the follower pin I25 engages the end I33 of the cam track I21, after which the pin I25 couples the cam I28 to the crank slide I28 and head I2I, and all of the parts rotate together against the frictional resistance offered by the brake I3 I.

A change in the crank throw can be made through rotating the azimuth motor 88 in the opposite direction, which effects rotation of the crank pin mechanism in a counter-clockwise direction (as seen in Fig. 13). The friction brake I3I again resists rotation of the cam I28, causing the follower pin I25 to track inwardly of the spiral cam groove I27 to the fullest extent, as determined by its engagement with the inner end I34 of the track. Such inward movement of the follower pin I25 positions the opposed crank pin 9'? in its outermost location, in which position it has a maximum throw. Here again, engagement of the follower pin I25 with the inner end I34 of the cam track I21 couples the cam I28 to the slide I22 and head I2I and causes unitary rotation of all of the crank parts against the frictional resistance of the brake I3 I. With the greater throw of the crank pin, the antenna 24, 33, 35 and the arm (not shown) of the azimuth potentiometer II9 are oscillated or caused to nod through a greater amplitude.

In the particular mechanism described in this application, the azimuth motor has different speeds, depending upon its direction of rotation. When rotated in a direction as to automatically move the crank pin 91 inwardly to its smaller throw, the motor operates at a high speed, in order to produce azimuth scanning and spiral scanning at a high speed, but small amplitude of arc. Reversal in the direction of rotation of the motor 88 increases the throw of the crank pin 91, but the motor is operating at a slower speed, to provide azimuth and spiral scanning at a wide amplitude and slow speed. The electric circuits for obtaining the operations just described will be referred to hereinafter.

In addition to providing driving and operating mechanisms for tilting and nodding the antenna, it may be rotated about the longitudinal axis of the apparatus by rotating the main drive spindle I5. A separate electric motor drive is current for the eperation of the transmitter;

receiver portion of the radarscan'ner apparatus, and which forms no part of the present 'invenf tion. The drive' between the spindle "if; andgen erator M2 is at a l to ratio,'and'the shaft t ll on which the bevel gear It; is secur5da1so serves to operate an erecting devicelliii'for restoring or positioning the nodding axi'sjfor azimuth scanning alone, to the Vertical, as will be 'de'scrib fin detail hereinafter. From the mechanisms described, it is possible to rotate the main drive spindle {5, forward wave guide L-sh'aped joint :3, lateral wave ,e 2!, oscillating feed horn portiori'gfl, 1onguuom rror ward extending feed horn portion 33, parabolic reflector 35, and all of the other parts secured "to the spindle arms 22, 2'5, about a longitudinal axis, well as oscillating the parabolic reffl lio'fafi and feed horn 2 4, 33 about the transverse axis of the feed horn shaft 25. "In addition, 'the'pai'a bolic reflector 35 may be tilted either upwardly or downwardly. It is desired to provide for selective operation of the apparatus through azimuth scanning alone, in 'which'therefiector 35 of the antenna may assume a Zero degree of tilt, :or a plus or minus degree of tilt; or to er; form spiral scanning; in whichthe degree of tilt must be 'zero and in which the main drive motor 35 is rotating the spindle L5 atthe s me'um that the az'imuth'motor s8 is oscillating the paraholic reflector 35 and feed horn 243,133; As stated above, oscillationcan take place throughtwo 'd'i f ferent amplitudes and at two' different speeds;

Rotation of the spindle l'5l also'sery'e's to I tate the erecting mechanism :43 for controlling a switch H34 in the spindle driving motor control circuit, which will indicate whether the imuth oscillatable axis is vertical or non-vertical. Duf ing rotation of the spindle H in the normal driv: ing direction, the shaft It! for the erecting mech; anism hi3 the generator I932 is rotating in a definite direction, as in a clockwise direction, as seen in Figs. 17 and 18. The erecting mechanism includes an arm Msa secured to the shaft 3 5! within housing 145 and having a counterweight 1) Hi5 on one end at one side of the shaft, and a counts ht E46, 'finger 1 3?], spring Mid and weight o. in a clockwise direction, as seen in l? and. 18', causes the finger weight I58 to swing outwardly to a slightextentagainst the tension the spring I l-9 and holdsthe finger Hi? spaced inwardly slightly of the housing wall Mifa so as to avoid rubbing thereagainst. However, reversal inthe direction of rotation or movement of the shaft Miami the parts enables assess the finger Hi! to move outwardly through a housingopeni ng 15 l and into a guide, formed by atioriar'y guide member'l52 and'amovable gu' de'member' composed of a lever 153 oscillatably mounted on a' pin I54 and urged toward the opposite guide member l52"b'y' a spring 154d se cured to the lever T53 and to the'l'iousing I45. The finger Id? hears against a plunger] 55,"which operates the switch I44, movingit to position indicative of the fact that the nodding ai iis' is at the vertical; Vfheh this position i's 'rea'chdQtlie' spindle driving motor I35 ceases its operation in a reversedirection, the spindle 5' being stopped with the azimu thaxisjvertical and thefeed'horn portion aw The ability of the drive motor 135 to function is also determined by the tilt mechanism. Since rotatioiiof the drive'motor ['35 is only to be p r: mitted when the parabolic reflector ass 'at its zero tilt position, the circuit throu hthe drive motor includes a switch I 55 which'is moved in acbhifdangi'with the position or degree of tilt of the reflector. Suchoperatioh is performed by attaching a rack 15'! to the tilt slide 53" which me with a pinion I53 attachedto a shaft 1'59 iournal d i a sw t h h usi g ts sec to the mainhousing it} of theapparatus (see Figs 2' and 4). A cam'ilif is secured to this shaft 59 and. is engageahle with a plunger'loz slid'alole in the housinglfiil and adapted to operate the er s witch i s t mei ii ii the sw t h a ex; intheevent the degree joftilt is other than zero, and t permit the switch to close in tneevem t angle of tilt'is zero. The 93m 16! c onsist's' of an arcuate peripheral'surface [63 and aflat surface m4. when the flat surface 15,4 is in contactwith the plunger or slid'ei62, the degree of tilt is zero and the plunger M32 is permitted to move toward the cam shaft I59" and allow the switch 55 5 close. i ,7 The tilt shaft I59 on which the tilt cam i6! secured also extends irito a tilt potentiometer 1,5 5 and is connected to a potentiometer armISB moy able over a suitable resistance [.61 contained therewithin for the purpose of producing any desired degree of tilt selected by the operator on the main control panel.

The apparatus also includes a pump and pulser motor I68 which is adapted to drive a pump I55 through a suitable reducing gear and crank mechanism (see Figs. 14, 15 and i6). Specifically, as disclosed in the drawings, a pinion 110 is secured to the motor shaft, meshing with a gear I'H affixed to a shaft I12 carrying ,a, worm engageable with a worm gear I'M secured to a crankshaft I15. One end of the crankshaft has a crank arm i'lfi attached thereto, whose crank pin HT mounts one end of a connecting rod [18 for reciprocating the piston (not shown) in the pump cylinder I69. The purpose of the pump is to pressurize the wave guide and maintain it under pressure conditions regardless of the operating altitude of the aircraft in which the apparatus is mounted, in order to prevent electrical breakdown of the R. F. elements. Air is drawn through ah 'air cleaner H79 and piping I80 into the pulp |69,'being discharged from the pump through suitable piping into the 'Wave guide. The air pump I69, by itself, forms no part of the present invention and requires no further descriptive details.

The pump motor 168 also operates a pulser mechanism is l, employed in connection with the 76 erecting of the nodding axis of the apparatus, to

the vertical when azimuth scanning alone is to be performed. This pulser mechanism is driven by the pump mechanism crank shaft I15, consisting of a known make-and-break mechanism embodying a cam I82 mounted on a shaft extension I83 and engageable with a movable contact arm I84, which may be engaged and disengaged from a stationary contact I85. As described below, this make-and-break device I8I forms part of the control circuit for the spindle driving motor By referring to the circuit diagram on Fig. 19, the electric contro1 of and interlock between the various motors, relays, switches, etc., will be understood. The control panel includes five decks, A, B, C, D, E, whose control arms I86 are secured for operation in unison over five different contacting positions, designated in the drawings by the numbers 1 to 5. The No. 1 contact is the off position. Movement of the arms I86 to the No. 2 contact provides a warm-up position. Their movement to the No. 3 and No. 4 contacts efiects the same operation of the device, the No. 3 contact affording a combined azimuth and tilt position for beacon scanning, while the No. 4 contact position is provided for azimuth and tilting for search scanning, the nature of the pulses applied to the R. F. sections being different for the two types of scanning. The distinctions between the two types of scanning, however, are immaterial to an understanding of the present invention. Movement of the arms I86 to the No. 5 contacts produces spiral scanning, in which the antenna is rotated about the longitudinal axis of the spindle I5, while it is simultaneously oscillated or nodded about the vertical axis of the apparatus.

The circuits include main positive and negative buses or lines 187, 188, which are connectible to the various motors and controls of the apparatus. The simultaneous placing of the manual control arms I86 in engagement with the No. 2 contacts will complete a circuit in deck E through a main power relay I89, which is then connected directly across the negative and positive buses, and which will pull its switch arm I98 into engagement with the spaced contacts I9I of the positive bus I81 and permit current to flow into the various electrical portions of the apparatus, passing through a thermal cut-out switch I92 in the positive bus line.

The azimuth motor 88 includes, in effect, two armatures I93, I94, comprising a high speed armature I93 and a low speed armature I94, connectiole in series with each other. The azimuth motor also has a shunt field I95 and a series field I96, there being a double pole, double throw reversin relay I91 for determining both the speed and the direction of rotation of the azimuth motor 88, which, as indicated above, determines the throw of the crank pin 91 and the amplitude and period of oscillation of the antenna paraboloid reflector and feed horn 24, 33 during azimuth and spiral scannings. The switch arms I98, I99 of the relay occupy the positions disclosed in Fig. 19, in contact with the lower switch contacts 288, 28I when the relay is not energized. Such energizing only occurs upon the closing of a nod control switch 282 in series with the relay coil 283, and serving to connect the coil across the positive and negative buses I81, I88 when the manual control arm I86 in deck E engages Nos. 2, 3, 4 and 5 contacts.

In the position disclosed, the switching arrangement connects the high and low speed armatures I93, 94 in series with each other, with the high speed armature I93 connected to the plus bus I81 through the lead 284, contact 208 and arm I98 and the low speed armature I94 connected in series with the series field I96 through the lead 205, contact 28I and arm I89, which, in turn, is connected to the negative bus I88, thus completing the circuit through the motor. The shunt field I is at all times connected across the positive and negative buses I81, I88. In view of the circuits just described, the azimuth motor 88 will rotate at a slow speed and in such direction as to produce shifting of the crank pin 91 to its greatest throw position, to provide a wide scanning angle.

In the event that the nod control switch 282 is closed, the circuit through the azimuth relay I9! will be completed, which will move the switch arms I98, I99 upwardly from the positions shown in Fig. 19, so as to reverse the polarity of the high speed armature I93 by connecting its former positive side to the negative bus I88 through the lead 204, contact 288 and arm I99. With such switching arrangement, the low speed armature I94 is disconnected from the circuit, although the series field I96 remains connected in series with the high speed armature I93. In view of the substantially lower resistance of the high speed armature alone, as compared to its series connection with the low speed armature previously described, and in view of its reverse polarity, the azimuth motor 88 is then rotated in a reverse direction and at a substantially higher speed. Such reversal in the direction of rotation effects a shifting of the crank pin 97 to its innermost position to provide a high speed, narrow azimuth scan of the antenna.

The tilt motor 68 may be operated and the angle of tilt of the parabolic reflector 35 controlled manually by the operator in accordance with the selective setting of a potentiometer arm 289 along a potentiometer resistance ZIO con nected across the positive and negative buses I81, I88, or in accordance with the zero tilt setting r of an arm M I contacting a second potentiometer resistance 2I2 connected across the positive and negative buses. The tilt motor will be operated and caused to rotate in such direction as to move the tilt return potentiometer arm I66 (connected to the shaft I59 carrying the pinion I58 engaging the rack I 51 secured to the tilt slide 82) to follow up or occupy the position corresponding to the setting of the manual tilt control arm 269 or the zero tilt arm 2| I, depending upon which of the two last-mentioned arms is connected in the circuit.

The tilt return potentiometer arm 86 is movable across the resistance I61 connected across the negative and positive buses I81, I88 through the leads 2 I3 and 2 I4, when the main switch arm I86 of deck E is turned from its No. 1 position into engagement with either the No. 2, 3, 4 or 5 contacts. As a result, current will flow through this potentiometer IE5, the side of the potentiometer connected to the negative bus being considered as negative and the side connected to the positive bus as positive. The tilt return potentiometer arm I66 is connected through a lead 2 I5 and a micropositioner 2 I 6 to the manual control arm I86 of desk A, which may make contact with either the No. 2 or No. 5 contact connected to the zero tilt arm 21 I, or with the No. 3 or No. 4 contact connected to the manual tilt control selector arm 209. Such circuit between the tilt return potentiometer arm I66 and the arca es zero and manual tilt control arms 5211., 209 is established through .an electromagnetic coil 21! of the micropositioner Zitadapted to attract, in one direction or another, a pivotally mounted armature 218 having oppositely extending contact arms 219, 22!) mounted thereon. Bi-voting of the armature in one direction engages one contact arm "2l'9 with .a fixed contact 2.2l from which a lead 222 runs to an upwardly tilting relay 233, while the pivoting of the armature in the opposite direction causes its other arm 22!! to engage a contact 1224 from which .a lead 225 runs to a downwardl tilting relay 22 6.

The circuits through the relays 223, 2 2 5 include the manual control arm 1:86 of deck B, which is adapted to engage either the No. 2, 3 or 4 contact, from which a lead i22 runs to a contact 228 of the vertical erecting switch M4, whose switch arm 22%) is disclosed in position indicative of the fact that the nodding axis is vertical, to permit the circuit through the tilt-up and tilt-downrelays 223, 226 to be completed to the negative bus 1558, through the line 23A! when the switch arm 2-86 of :deck D is engaged with either :the No. 2,3 or 4 contact.

The tilt-up relay 223 has a lead 23! running from its electromagneticcoil 232 to a contact 233 which is normally engaged by an arm 234 movable by the tilt-down relay 2-2-6, this arm being connected to a lead 235 running to the positive bus 181. Similarly, the tilt-down relay 225 has its electromagnetic coil 2:35 connected to a contact 231 engaged by an arm 2-33 controlled by the tilt-up relay 223 and connected to the lead 235 running to the positive bus.

The tilt motor 58, which has a permanent mag netic field, may be connected across the positive and negative buses I 81, 138 so as to produce its operation in either a forward or reverse direction, depending upon the tilting of the reflector 35 upwardly or downwardly. The upperlead 239 from the tilt motor armature is connected to a contact 250 which is engageable by the arm 234 notuated by the tilt-down electromagnet coil 23S, and which is also connected through a branching lead 2M to a contact 2 32 engaged by an arm 243 operated by the tilt-up coil 232 and having a lead 244 running to the negative bus I58.

Similarly, the other side of the armature has a a lead .245 connected to .a contact 246 engaged by an arm 24! movable by the tilt-down relay 2 25, the lead 245 also running to a contact 248 engagee ble by the upper arm 23:; of the tilt-u relay 223. The upper arms 23-4, 238 are'connected, as indicated above, to the positive bus Hi1, while the lower arms 24.3, 24? are connected through the lead 244 to the negative hus I88. A resistance 249 is also connected across the tilt motor armature in order to provide an electric brake on the motor and to dissipate the inductive kick present when the tilt motor circuit is opened.

As disclosed in the circuit diagram, neither the tilt-up nor tilt-down relay 223 or 226 is energized and no current flows through the tilt motor 68,

the tilt angle of the reflector 35 rema ning on changed.

Let it be assumed that the switch arms I 86 are engageable with the No. 2 contacts, which places the zero tilt arm 2H in the circuit, and that the reflect-M35 is tilted downwardly, which causes the tilt return potentiometer arm I55 to occupy a corresponding position to the left of the resistance midpoint, as disclosed in the circuit diagram.

Since the tilt return potentiometer resistance 1-5 is connected directly across ithepositive and negative :huses 1e71, 1838., a greater resistance provideo. on :the negative side of the potentiometer than on the positive side, which will cause the tilt arm "I66 tohave a positive polarity, and also the electromagnetic micropos'itioner coil '25! at point '2 50 to have a positive polarity :as compared to the polarity .of the other end 255 of the coil, since the zero tilt potentiometer arm 21! con nected to it'is at the midpoint along its resistance 2 L2. Accordingly, the electromagnetic coil 2 ii is energized to attract the armature Zita and swing it in a clockwise direction about its pivot and moves its arm 2 l 9 into engagement with the tiltup contact 224, completing the circuit to the tiltup relay 223. Energization of this relay pulls its associated contact arms 238, 343 upwardly, so as to engage the upper arm 23% with the upper contact 2-48 of the tilt motor 6'8, and its lower arm 2453 with the lower contact 242 of the tilt motor. :Su-ch contact engagement places a positive polarity on the lower lead 245 of the tilt motor and a negative polarity on it upper lead 2-35, causing the tilt motor 68 to rotate in an up-tilt direction to reduce the angle of tilt of the reflector 35 from the downward angle toward a zero angle. As such reduction occurs, the tilt return potentiometer arm 166 is moved through the rack I51 and pinion 15B toward its midpoint, along the resistance H5! corresponding to the zero setting on the control panel, decreasing its positive polarity. When such midpoint is reached, the polarity of the arm IE5 is neutral, and flows through the electromagnet 2", allowing the armature 2i3-to assume a'neutral position out of engagement with the tilt-up contact 221, the tilt-up relay 223 becoming deenergized and the contact arms 23s, 2423 assuming their initial positions, as disclosed in the diagram, breaking the circuit to the tilt motor.

Conversely, if the tilt return potentiometer arm ['55 had been in a position to the right of its neutral point, as seen in the wiring diagram, in view of an upward .tilt angle, its polarity would havebeen negative, making the lower end 25!! on the .coil .Zil' negative and. its other end 25! relatively positive. causing the armature 2 i 8 to swing in a counter-clockwise direction into engagement with contact .224, completing the circuit through the tilt-down relay .225, which moves its upper and lower arms 234, 2d: upwardly into engagement with the tilt motor contacts 2%.. 24! connecting the lower lead 245 to the negative bus 253% and the upper lead 239 to the positive bus @551, or reversely to the aforementioned connections, reversing the direction of rotation of the tilt motor 58, which tilts the reflector down toward its zero position. When such zero position is reached, the tilt return potentiometer arm 556 would occupy a midpoint position, so that no difference of potential would exist across the coil 241, the armature 2H3 returning to its inoperative position, breaking the circuit through tilt motor, which is stopped promptly by the eleciric bre resistance 249.

lillovement of the manual control arm in deck A to the No. or No. l position would 1 ve placed the manual tilt control 299, 2.2 3 in the circuit, rather than zero tilt control 2! l, 2 i 2. However, the operation of the tilt return potentiometer .fifi would have been the same. The degree of tilt, either .up or down (positive or negative), could be selected within the limits of the a paratus by moving the manual tilt control arm 2'09 along its resistance 2m, and the arm I66 on the tilt return potentiometer would be caused to follow up to this preselected manual position, in view of the current and the direction of current caused to pass through the electromagnetic coil 2 I 1 of the micropositioner 2 I 6.

For the purpose of preventing the tilt motor 68 from overrunning the manual tilt control or zero tilt settings, with resultant hunting, a resistance 252 is connected between the tilt-down lead 225 and the point 25I of the coil 2I'I, and another resistance 253 between the tilt-up lead 222 and the other end 25 of the coil. When the circuit through the tilt-up lead 222 is completed, a negative polarity is transmitted through the lower resistance 253 to the point 250, reducing its positive polarity slightly, and causing a zero potential difference across the coil 2| I to occur slightly before the tilt return potentio lleter arm I 66 has been moved into exact correspondence with the position of the manual tilt control arm 209 or zero tilt arm 2. As a result, the circuit to the tilt motor 68 is opened a fraction of a second, or a fraction of a tilt motor revolution, before the tilt return potentiometer arm I55 has been moved to such position of correspondence, there being sufficient inertia in the tilt mechanism parts to continue their movement slightly so as to bring the parabolic reflector 35 and the tilt return potentiometer arm Ifit into exact correspondence with the manual tilt control or zero tilt control settings.

Conversely, completion of the circuit through the tilt-down relay 228 will provide a slight negative potential through the upper resistance 252 on the upper end 25! of the coil 2lI, which then has a predominant positive polarity, the potential difference across the coil 2I'I being reduced to zero slightly in advance of movement of the reflector 35 and tilt return potentiometer arm IE into exact correspondence with the zero tilt or manual tilt control potentiometer arms 2| I or 209.

The motor I35 for rotating the driving spindle I5, the erecting mechanism I44 and generator :42 can be variously connected in the circuit, depending upon the position of the manual control arm I85 with respect to the various contaste. The motor will only be in position for driving the spindle in its normal direction during spiral scanning, when the arms I86 engage the No. 5 contacts, but it may be connected in the circuit when the arms are in engagement with the No. 2, 3 and 4 contacts, so as to be capable of operating in a reverse direction for the purpose of erecting the oscillating axis about which the antenna is to nod to the vertical, when azimuth scanning alone is desired.

It is to be noted that the No. 2, 3 and 4 contacts in deck D are connected to the negative bus I83 and that the lead 230 runs from the arm i555 to the vertical erecting switch I44, which may occupy two positions, one with its arm 228 in engagement with the left contact 228 when the oscillating axis is vertical, and the other in engagement with another contact 254 when the oscillating axis is not vertical, in series with the pulser or make-and-break device I8I which is constantly rotated by the pump motor I63 connected across the positive and negative buses I81, I513. The other end I85 of the pulser or makeand-break device is connected to pulsing control line 255 running to a relay 256, which is relatively fast acting, being of the solenoid type, whose plunger 251 is adapted to bridge a pair of spaced contacts 258 in a line 259 runnin to the armature 260 of the spindle drive motor.

The coil 25I of the relay 256 is connected to a line 262 having a contact 263 and also a branching line 26 2 running to another contact 265. The first-mentioned contact 263 may be engaged by a relay arm 266 connected to a lead 26! running to the negative bus I88. The other branching contact 265 may be engaged by a relay arm 268 connected to a lead 269 in series with the motor field coil 210 and connected to the positive bus I81. These last-mentioned arms are actuated by a relay 2II, of the double pole, double throw, reversing type, having a slower rate of operation than the solenoid relay 256, being of the clapper type and having one end of its coil 212 connected to the negative bus lead 261, and its other end connectible through the tilt interlock switch i513 to the lead 23!] running to the arm I86 in deck D.

The other lead 213 from the spindle drive motor armature 266 has a branching lead 214 through a resistance 215 to a contact 216 engageable by the upper clapper relay arm 286, and another branching lead 216a running to a contact 211 engagcable by the lower clapper arm 268, in order to determine the direction of rotation of the drive motor, depending upon the position of the clapper relay switch arms 266, 268.

As aforesaid, the spindle driving motor can only be rotated in its normal direction in the event that the tilt angle of the reflector is zero. Such rotation of the drive motor to obtain spiral scanning occurs when the manual arms I86 of decks C and D are in engagement with the No. 5 contacts, which completes the circuit through the clapper relay 2' and causes it to move the switches 255, 268 upwardly into engagement with the upper contacts 263, 277, placing the lower lead 2'35, 2'53 from the drive motor in series with the series field 210 and connecting it to the positive bus I81. Momentarily, the circuit through the upperlead 259 of the drive motor is open, but the engagement of the upp r relay arm 266 with the upper contact 263 completes the circuit through the fast operating solenoid relay 256, through the lead 255 and arm I86 of deck 0, causing it to attract its plunger 255 and bridge the contacts 258 across the upper lead 259 and connecting it to the negative bus I88, thereby completing the circuit through the drive motor I35, which then rotates in its normal direction for rotating the scanner mechanism about the longitudinal axis of the apparatus.

When the spindle I5 is to be rotated in a normal direction by the spindle drive motor I35, the manual controls I86 have been moved into engagement with the No. 5 contact, which places the zero tilt potentiometer arm 2II in the circuit. In the event that the tilt angle is different from zero, the tilt interlock switch will be open, preventing completion of the circuit to the drive motor I35 so as to cause its rotation in its normal direction. The tilt mechanism must, therefore, first restore the tilt angle to zero, which causes the cam IEI to allow the tilt interlock switch I to close, whereupon the motor I35 may be rotated or driven in the manner indicated above.

In the event that azimuth scanning alone is desired after spiral scanning (which includes rotation of the spindle) has occurred, the manual control mechanism is moved until the arms I86 engage either the No. l or No. 3 contact, Such contact effects an automatic erecting of the azimuth oscillating axis to the VerticaL bymeans of the circuits now to be described. Engagement of the contact arms I86 with either the No. 3 or No. 4 contact connects the lead 230 to the negative bus and also places the make-and-break pulser device I84, I85 in the circuit with this lead, because the lack of vertical positioning of the spindle will mean that the erecting switch arm 226 has moved to its other position against the contact 254, in series with the pulser contact merchanism I84, I85. A circuit through the clapper type relay 21I is also completed, butno current flows therethrough since bothsides of the relay coil 212 are connected to the negative bus I88. However, the circuitthrough the rapid operating relay 256 is completed intermittently, in accordance with the making and breaking of contact by the pulser device I8I, whichisbeing driven steadily by the pump motor I68. Such completion of the circuit through the coil 26I effects a bridging of the contacts-258, but places the upper lead 259 ofthe drive motor in series with the field coil 210 connected to the positive bus I81, through the lower contact 265 and arm 268, and-places the lower lead 213 of'the drive motor in the series with-the'resistance 215 and in the circuit with the negative bus I61, through the contact 216 and switch arm 266. As a result,

the'drive motor rotates in a reverse direction because of the reverse polarity therethrough, and, inview of the resistance 215 in series .with the armature 260 and the intermittent application of current to the rapid operating relay 256, which intermittently makes and breaks contact across the spaced contacts 258, the motor is rotated in a rearward direction intermittently at acomparatively slow "speed, untilthe spindle I has been placed insuch position that the vertical axis of nodding or oscillation has been restored, as indicated byreverse movement of the erecting mechanism I44 and engaging ofthe finger- I41 with the plunger I55, which moves-the s'witch. 229 over to the left con'tact 228 shown in the diagram, thereby breaking the circuit to the relay 256 and tothe drive motor I35, which then remains stationary. The erecting mechanism I44 breaks the motor circuitwhenthefeed horn shaft25 isvertically disposed, the yoke I41 and slide 53 being above the longitudinal axis.

In. the event that azimuth scanning alone is desired, and in the furthereventuality that the manual tiltcontrol 209..has. been set for either a positive or negative degree of tilt, the switching of the main arms I86'fromtheir No.5 contacts to .either the No. 4 or the N0. 3 contacts will cause the tilt returnpotentiometer- I65 and the manual tilt control to act in concert and operate the micropositioner switch 2I6 in such manner as to restore the degree of tilt to the selected extent.

As noted above, during normal spindle rotation by the drive motor I35, both the slow and high speed relays -21I,-256 are energized with'the arms I86 engaging the No. -5 contacts. --Upon switching to the No. 5 contacts, the circuit through the high speed relay 256 cannot be completed until the slow speed relay 21I has pulled up its arms 266, 268 into engagement with the upper contacts 263, 261, whereupon the high speed relay 255 may close the motor circuit for manual rotation. In switching from No. 5 to No. 4 or No. 3 contacts, however, the circuits through both relays are opened, but the high speed relay 256 breaks the circuit at 258 to the motor I35 before the slow speed relay arms 266,

268 can begin moving down,.thereby preventing Such nodding may occur through a wide angle andat a slow speed,or through a narrow angle and at a. higher speed. In addition, azimuth scanning alone cantake place through either of the aforementioned amplitudes of oscillation and atthe aforementioned oscillating speeds. In addition, during azimuth scanning alone, the tilt angle of the parabolic reflector 35 may be changed either upwardly or downwardly with respect to the horizontal, Within-limits, or the tilt angle ma remain at a zero position. The mechanism is designed totransmit radio frequency electrical energy through the Wave guide and its feed horn, and through the windows ontothe reflecting surface in varying directions, depending upon the extent of scanning and the type of scanning. The

impinging of such beam on a target will produce its echoing orreflection back to the reflector for transmission through the windows, feed horn and the'wave guide to the receiving mechanism for proper indication on-the radar scope of the angle or quadrant in which the target islooated, in view of the synchronization between the azimuth scanning and the azimuth potentiometer II9.

Assurance ishadfthat the nodding axis is automatically restored to the vertical when azimuth scanning alone is to occur, and assurance is also had that the spindle I5 cannot be rotated unless the tilt angle is zero, the movement to a zero position "being automatically accomplished as a result of selecting the spiral scanning position. Conversely, the shifting from spiral scanning to azimuth -scanning alone will automatically repos'ition the preselected angle of tilt.

WhileI haveshown the preferred form of my invention," it is to .be understood that various changes may be made by those skilled in the art without departing from the spirit of the invention as defined in theappended claims.

.Havingthus described my invention, what I claim. and,desire .to secure by Letters Patent is:

.1. Radar scanninglappar'atus, including a spindl'e rotatable aboutfjlOngitudinal axis, a feed horn shaft carried by said spindle for oscillation aboutanaxiswhich is transverse to thelongitudinal axis, afreflector carried by said feed horn shaft for tilting aboutathird axis at right angles to said is guuainai and. transverse axes, means for rotatihgjsaid spindle and'oscillating said feed hornsh'aft, means for tilting saidfreflectonand meansresponsive to movement of said reflector about said third axis forpreventingoperation of said spindle rotating. means unless the angle of tilt ctsaidfreilectorjwith es ect to said longitndin lasisis ar 2. Radar scanning apparatus, including an antenna, a first means for supporting'said antenna for rotation about a longitudinal axis, a second means for supporting said antenna on said first means for oscillation about a transverse axis at right angles to said longitudinal axis, a third means for supporting said antenna on said second means for tilting about a third axis at right angles to said longitudinal and transverse axes, means for rotating said first means, means for oscillating said second means, means for tilting said third means on said second means, and means responsive to movement of said antenna about said third axis for preventing operation of said means for rotating said first means unless the angle of tilt of said antenna with respect to said longitudinal axis is zero.

3. Radar scanning apparatus, including an antenna, a first means for supporting said antenna for rotation about a longitudinal axis, a second means for supporting said antenna on said first means for oscillation about a transverse axis at right angles to said longitudinal axis, a third means for supporting said antenna on said second means for tilting about a third axis at right angles to said longitudinal and transverse axes, means for rotating said first means, means for oscillating said second means, means for tilting said third means on said second means, and means for maintaining the angle of tilt of said antenna with respect to said longitudinal axis at zero degrees during rotation of said first means about said longitudinal axis.

4. Radar scanning apparatus, including an an tenna, a first means for supporting said antenna for rotation about a longitudinal axis, a second means for supporting said antenna on said first means for oscillation about a transverse axis at right angles to said longitudinal axis, a third means for supporting said antenna on said second means for tilting about a third axis at right angles to said longitudinal and transverse axes, a fourth means for rotating said first means, a fifth means for oscillating said second means, a sixth means for tilting said third means on said second means, means responsive to movement of said antenna about said third axis for preventing operation of said fourth means unless the angle of tilt of said antenna with respect to said longitudinal axis is zero, means for controlling operation of said fourth means, and means operable upon movement of said controlling means to a position for initiating operation of said fourth means for causing said sixth means to tilt said antenna to a zero tilt angle.

5. Radar scanning apparatus, including a spindle rotatable about a longitudinal axis, a feed horn shaft carried by such spindle for oscillation about a transverse axis, a reflector carried by said feed horn shaft for tilting about a third axis at right angles to said longitudinal and transverse axes, means comprising an electric motor for rotating said spindle, means comprising an electric motor for oscillating said feed horn shaft, means comprising an electric motor for tilting said reflector about said third axis, means responsive to movement of said reflector about said third axis for preventing operation of said spindle rotating motor unless the angle of tilt of said reflector with respect to said longitudinal axis is zero, means for controlling operation of said spindle rotating motor, and means operable upon movement of said controlling means to a position in which it may initiate operation of said spindle rotating motor for causing said tilt motor to move said reflector to a zero tilt angle.

6. Radar scanning apparatus, including a spindle rotatable about a longitudinal axis, a feed horn shaft carried by said spindle for oscillation about a transverse axis, a reflector carried by said feed horn shaft for tilting about a third axis at right angles to said longitudinal and transverse axes, means comprising an electric motor for rotating said spindle, means comprising an electric motor for oscillating said feed horn shaft, means comprising an electric motor for tilting said reflector about said third axis, means responsive to movement of said reflector about said third axis for preventing operation of said spindle rotating motor unless the angle of tilt of said reflector with respect to said longitudinal axis is zero, means for controlling operation of said spindle rotating motor, means operable upon movement of said controlling means to a position in which it may initiate op eration of said spindle rotating motor for causing said tilt motor to move said reflector to a zero tilt angle, means for reversing the direction of rotation of said spindle rotating motor to vertically position said feed horn shaft transverse axis, and means for stopping said spindle rotating motor upon vertical positioning of said transverse axis.

7. Radar scanning apparatus, including an antenna having a longitudinal axis, a first means for supporting said antenna for rotation about said longitudinal axis, a second means for supporting said antenna on said first means for oscillation about a transverse axis at right angles to said longitudinal axis, a third means for supporting said antenna on said second means for tilting about a third axis at right angles to said longitudinal and transverse axes, said mounting means mounting the antenna for independent rotation or oscillation about each of said axes and means for rotating, oscillating and tilting said antenna about said longitudinal, transverse and third axes.

TOMLINSON I. MOSELEY.

REFERENCES CITED The following references are of record in the file of this patent:

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